Hydrogen release for a heat pipe



March 31, 1970 W. T. GEYER HYDROGEN RELEASE FOR A HEAT PIPE 3 Sheets-Sheet 1- Fled Oct. 25, 1968 INVENTOR WALLACE T, GEYER wd SW ATTORNEY March 3l, 1970 w. T. GEYER HYDROGEN RLEASE FOR A HEAT PIPE 3 Sheets-Sheet 3 Filed Oct. 25, 1968 United States Patent O 3,503,438 HYDROGEN RELEASE FOR A HEAT PIPE Wallace, T. Geyer, Des Peres, Mo., assignor to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Filed Oct. 25, 1968, Ser. No. 770,558 Int. Cl. F28d 15/00; F24h 1/00 U.S. Cl. 165-105 10 Claims ABSTRACT F THE DISCLOSURE BACKGROUND OF THE INVENTION Railway tank cars are commonly heated by a system includ-ing an extensive array of steam pipes. It has been proposed to heat such cars by -a `so-called heat pipe, exa-mples of which are disclosed in Patent No. 3,229,759 to G. M. Grover and Patent No. 3,468,300 to W. T. Geyer et al. When the heat pipe uses water as the vapor-izable huid therein, it is found that the water dissociate-s. The resulting oxygen is absorbed by combining with the metal of the heat pipe. The resulting hydrogen, however, accumulates, and if its pressure reaches or exceeds the value which the heat pipe is designed to withstand, the heat pipe may explode. It is important, therefore, to keep the hydrogen pressure at safe levels. This problem may arise, of course, not only when water is used, but when any vaporizable fluid containing hydrogen is used in the heat pipe.

SUMMARY OF THE INVENTION A heat pipe for a railway tank car uses water as its fluid. The heat pipe includes a reservoir outside the tank. A plug is welded in the wall of the reservoir and a nickel tube extends through a bore of the plug. A `coiled palladium tube is welded to the inner end of the nickel tube, and the inner end of the palladium tube is sealed. Since palladium is pervious to hydrogen, it passes into the palladium tube and then through the nickel tube to the atmosphere.

BRIEF DESCRIPTION OF THE DRAWING The invention is illustrated in the accompanying drawing, in which:

FIGURE 1 is .a side elevation of a railway tank car having a Iheat pipe in the tank and extending out of the tank into -a furnace.

FIGURE 2 is a top plan fview of the heat pipe, with a portion of the tank broken away.

FIGURE 3 is a front elevation of the heat pipe and its reservoir.

FIGURE 4 is a sectional view taken along line 4-4 of FIGUR-E 2.

FIGURE 5 is a partial sectional view along line 5 5 of FIGURE 4.

FIGURE 6 is -a partial sectional view of the hydrogen release device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an insulated railway tank car is generally indicated 10 in FIGURE 1 yand comprises an inner tank 12, and outer jacket -14 extending about the 3,503,438 Patented Mar. 31, 1970 circumference of tank 12, and a layer of insulating material 16, such as a polyurethane foam material or -ber glass, between outer jacket 14 and inner tank 12. A center sill 18 extends the length of railway car 10, with outer jacket 14 being attached to the outer sides of center sill 18. A coupler 19 i-s mounted within each end of center sill `18. A wheeled truck 20 is provided adjacent each end of railway tank car 10.

Mounted on an end of railway tank car 10 is furnace 22 of the open flame type. To supply fuel, such as propane ga-s, to furnace 22, a fuel container 24 is mounted on each side of railway tank car 10 and has a fuel line 26 leading to furnace 22. Mounted within inner tank 12 for heating liquid lading therein to temperatures of 500 F. or greater is a heat pipe 28 for transferring heat from furnace 22 to the lading within inner tank 12. Heat pipe 28 include-s an inner portion 30 mounted within tank 12 and an outer end portion 32 which extends through the adjacent end of inner tank 12 and outer jacket 14 within furnace 22. Brackets 34 support heat pipe section 30 within the tank at a height -above the bottom of the tank. As shown in FIGURE l, heat pipe 2S slopes downwardly to outer end portion 32 within furnace 22. Inner portion 30 compri-ses a condenser portion of heat pipe 28 and outer portion 32 comprises the evaporator or boiler portion of heat pipe 28.

Referring to FIGURES 2 to 5, heat pipe 28 is welded to a reservoir 40 in the form of a transverse stainless steel pipe located beyond the furnace and extending across one end of the car. The heat pipe is closed by an end cap 42. Reservoir 40 has a nipple 43 through which it is charged with liquid and an inert gas, such as argon, and ha-s a safety head 44, including a rupture disc, for relieving excessive pressure. The far end of the heat pipe has a welded end cap 46 provided with a stainless steel ber plug 48, for providing capillary action and insulation at the end. As shown in FIGURE 4, heat pipe portion 32 has on its inner surface a wick 50 which extends into the reservoir as indicated at 52. The wick m-ay include sintered iibrous porous material 54 and a nu-mber of layers of ne =mesh stainless steel wire screen 56, and is reduced in thickness as it extends from the evaporator end, near heater 22, to condenser portion 30 of the heat pipe within tank 14. In condenser portion 30 of heat pipe 28, the

wick may consist of one or more layers of Kscreen 60 `separated from the wall of pipe 28 by a corrugated screen I62, best shown in FIGURE 5. This wick structure extends out to the end of the pipe. The wick is held in place by coil spring 64, which is anchored to pin 66 on ring 68 at one end, and anchored to spring clip 70 at the other end. Corrugated screen 62 provides large pores for longitudinal flow, while `at the same time maintaining some wicking action, which is primarily provided by surface layers 60. The construct-ion of the heat pipe described above is fully disclosed in application Ser. No. 765,208 tiled Oct. 4, 1968 by George M. Grover and Edward L. Coyle, for Heating System for a Railway Tank Car 0r the Like.

The upper wall of reservoir 40 is provided with a hydrogen relief device 72. A plug 74!l is welded in an opening 76 in Wall 78 of reservoir 40. Tube 80 extends through a central bore 82 of plug 74 and is welded to the plug. A coiled tube generally indicated 84 is closed at its inner end 86 and is sealed at its outer end to tube 80. ICoiled tube 84 is formed of material containing palladium, such as a silver-palladium alloy and tube is formed of nickel. In one embodiment of the invention, tube 84 has an overall length of twelve inches and an overall outer diameter D of 'Vs inch. The outer diameter of the tube Wall is .063 inch and the tube wall is of a thickness of .003 inch.

It is well known that palladium is pervious to hydrogen. Hydrogen formed by dissociation of water in heat pipe 28 passes into the interior of tube 84 and then through tube 80 to the atmosphere, and this is preferable to discharging the hydrogen into tank 14, which might have a lading affected by hydrogen. The amount of hydrogen required to be exhausted in one embodiment of the invention, using a rather short heat pipe, is believed to be about l to 20 cc. per 24 hours, but exhaustion of larger amounts may be required, depending on the size of the heat pipe and the temperature. The device 72 has the desirable characteristic of providing a hydrogen emission which varies with pressure. The oxygen produced by the dissociation of water in the heat pipe 28 combines with the materials of the heat pipe and is thus absorbed.

I claim:

1. In a heat transfer pipe containing a capillary wrck and a vaporizable liquid which releases hydrogen upon dissociation due to high temperatures, the improvement comprising relief means in said heat transfer pipe selectively permeable by hydrogen for conveying hydrogerout of said heat transfer pipe, whereby the development of a dangerously high pressure of hydrogen gas is prevented.

2. Apparatus according to claim 1, wherein said relief means includes a palladium containing seal for an open ing in said heat transfer pipe.

3. Apparatus according to claim 2, wherein said heat transfer pipe includes a reservoir for said liquid, said seal being located in a wall of said reservoir.

4. Apparatus according to claim 2, wherein said opening in said heat transfer pipe is in a wall thereof and said seal includes a hollow body having a wall containing palladium and an opening communicating with the opening in the wall of said heat transfer pipe.

5. Apparatus according to claim 4, wherein said hollow body is a tube having a closed end and an open end.

6. Apparatus according to claim 5, including a second tube extending through said wall of the heat transfer pipe to form said opening therein, the first mentioned tube having its open end joined to said second tube.

7. Apparatus according to claim 3, including a railway tank car having a tank to be heated by said heat transfer pipe and inclosing a portion thereof, another portion of said heat transfer pipe, including the reservoir, being located outside said tank, whereby the hydrogen is discharged to the atmosphere.

8. In a railway tank ear including a tank shell for the transport of lading adapted to be heated to a predeterrnned temperature, a heat transfer pipe having at least a portion thereof mounted within the tank shell, heat producing means mounted on the tank car outwardly of the tank shell to heat a portion of the heat pipe, said heat pipe comprising an outer circumferential wall, a porous capillary wick within the circumferential wall, a vaporizable uid within the wall including water dissociating into hydrogen upon the reaching of high temperatures, and hydrogen relief means communicating with said heat transfer pipe to release hydrogen from said heat transfer pipe, said relief means including a palladium containing seal exposed to the hydrogen and diffusing said hydrogen from the heat pipe thereby preventing a h igh pressure of hydrogen gas within the heat transfer pipe.

9. In a container having material adapted to be heated to a predetermined temperature, a heat transfer pipe having at least a portion thereof mounted within the container, saidv heat pipe comprising an outer circumferential Wall, a capillary wick within the wall, a vaporizable uid within the wall including water dissociating into hydrogen upon the reaching of high temperatures, and hydrogen relief means communicating with said heat transfer pipe to release hydrogen from said heat transfer pipe, said relief means including palladium exposed to the hydrogen and diffusing said hydrogen from the heat pipe thereby preventing a high pressure of hydrogen gas vn'thin the heat transfer pipe.

10. In a heat transfer pipe containing a wick and a vaporizable liquid including water which releases hydrogen upon dissociation due to high temperatures; the improvement comprising hydrogen relief means in communication with said heat transfer pipe to remove pressurized hydrogen from the transfer pipe, said hydrogen relief means including a palladium containing seal exposed to the hydrogen and diffusing the hydrogen from the heat pipe thereby preventing a high pressure of hydrogen gas within the heat transfer pipe.

References Cited UNITED STATES PATENTS 3,229,759 1/1966 Grover 165-105 ROBERT A. OLEARY, Primary Examiner A. W. DAVIS, J R., Assistant Examiner U.S. Cl. X.R. 

